Lead checking device for globoidal worms



Oct. 20, 1936. H, PELPHREY 2,057,970

LEAD CHECKING DEVICE FOR GLOBOIDAL WORMS Filed April 2, 195e 4 sheets-sheet 1 ORNYS,

Oct. 20, 1936.` H. PELPHREY LEAD CHECKING DEVICE FOR GLOBOIIDAL WORMS Filed April 2, 1956 4 Sheets-Sheet 2 Oct. 20, 1936. H. PELPHREY LEAD' CHECKING DEVICE FOR GLOBOIDAL WORMS -4 Sheets-Sheet 3 y Filed April 2, 1936 Oct. 20, 1936. H..|=ELPHREY LEAD CHECKING DEVICE FOR GLOBOIDAL WORMS 4 Sheets-Sheet 4 Fiied April 2, 1956 V INVENTOR. u

Harry )Dlyrfgc A TTORNEYS.

Patented' oct; 2o, 1936 UNITED STATES PATENT oFF'l'cE aosas'io LEAD cnEcxrNG DEVICE non.v

GLOBOIDAL WOBMS Harry Pelphrey, Detroit, Mich., assignor to Michigan Tool Company, a corporation of Delaware Application April 2, 1936, Serial No. 72,238

21 Claims. (Cl. :i3-174) Objects of the present invention are to pro-` vide agear checking device of the just stated typ; to provide suchA a device embodying means to move a worm and a checking instrument in timed relation, the checking instrument being -effective to record or to respond to variations from a selected value of the lead, pressure angle, or the tooth spacing; to provide such a device embodying a finger corresponding tovone tooth of a worm wheel of mating capacity with the worm to be tested, and embodying means to move the iinger in a circular path concentric` with the axis of such worm wheel, in timed relation to the rotationof the worm; to provide such a device in so which the finger is pivotally supported and adapted to bear against a tooth face of the worm, and having recording mechanism associated therewith, adapted to respond to a pivoting of the nger aboutv its pivotal axis as influenced by variations inthe lead, pressure angle, or tooth spacing of the Worm; to provide such a machine inV which the finger coincides with a line representing an extension' of avworm tooth face; and to provide such a device in which a movement of said finger from said coinciding position, as infiuenced by variations from a desired value in the pressure angle, lead or tooth spacing. results' 'in an indication as to the character and magnitude of such variation.

v Further objects of the present invention are to provide a checking device of the general character above stated, and embodying means to vary the center distance between the worm and the checking instrument in order to accommodate the deviceto worms of different sizes and in order to permit ready checking of the pressure angle of a worm; to provide such a device in which the finger is supported upon a table which is mounted upon a rotatable support and is movable transversely of said support; and to provide such a device embodying driving means common to the worm and to the checking device in order to effect movement thereof in correspondence with each other. f

Further objects of the present invention are to provide va gear checking device of the general character above. stated, which is selectively adjustable to accommodate gears of different leads and pressure angles; to provide a device in which the radial spacing between the nger and its center of bodily rotation is selectively and accurately adjustable; and to provide'such an arrangement embodying improved mechanism to efi'ect the radial adjustment of the finger.

Further objects of the present invention are c to provide a gear checking device embodying means to index a worm and a checking instru-4 ment in timed relation, in which the indexing means are individual to the .Worm and to the checking instrument respectively; in which means 10 are provided to change the relative rotative positions of the worm and of the indexing device, and

of the checking finger and theworm; in which the means for indexing the worm and the checking device include toothed discs, and detent l5 mechanism associated therewith to eilect predetermined angular advan'ces oi each disc; to provide such a device in which one of the indexing devices includes a plurality oi spaced pins, and detent mechanism associated therewith and re- 20 tractable to permit advanceof the associated member past a selected number of such pins corresponding to a desired angular advance thereof; and to provide such a device including means to eiect a continuous advance of one of the mem- 25 bers and having cooperating means to accurately record thel angular advance so effected.

With the above and other objects in view, which appear in the following ldescription andi in the appended claims, various preferred em- 30 bodiments of the present invention are shown lin the accompanying drawings, throughout which corresponding reference 'characters vare used to designate corresponding parts and in which:

Fig. l is a view in top plan of one embodiment 35 of the present invention;

Fig. 2 is a detail view illustrating a preferred face structure of the checking finger of the mechanism shown in Fig. 1:

Figure 3 is a view-in side elevation of the struc- 40 ture shown in Fig. 1;

Figure 4 is a top plan view of a modified embodiment of the 'present' invention;

Figure 5 is a detail view in vertical section, taken along the line 5--5 of Fig. 4; 45

Figure l6 is a detail view in vertical section, taken along the line 6-6 of Fig. 4;

Figure 7 is a sectional view in side elevation corresponding in general to Fig. 4, but having certain of the elements of Fig. 4 omitted there- 50 from;

Figure 8 is a detail view in vertical section, taken along the line 8-8 of Fig. 4; I f

Figure 9 is a partial View illustrating a modiiied indexing means for the checking instrument; and 55 Figure 10 is a fragmentary view illustrating a second modified arrangement for indexing the checking instrument.

Worm gears of the globoidal or Hindley type,

to which the present invention particularly relates, are characterized in that lines drawn, in a plane of the axis of the worm, as extensions in such plane of the tooth faces of the worm, are all tangent to a circle, which may for convenience be called the base circle of the worm, and which is concentric with the axis of a Worm wheel of mating capacity with the worm and positioned in mating relation thereto. For each worm, the spacing between the center of the base circle thereof and the axis of the Worm is determined primarily by .the radius of the Worm wheel with which the worm is designed to mate, and the radius of the base circle is determined by the pressure angle of the teeth of the worm.

The tangential relation between lines representing extensions of the tooth faces and the base circle of the worm, as above generally stated, is utilized in the gear checking construction of the present invention, although, as will appear from a complete understanding of the present invention, certain of the features and advantages thereof are useful in connection with the checking of gears of other than the globoidal type, and may be practiced in constructions not primarily based upon the just stated principle.

Considering nowl the various preferred constructions in detail, and referring first to Figures 1, 2, and 3, the worm 20 to be checked is supported upon an arbor 22, which in turn is rotatably supported between head and tail stocks 24 and 26, respectively, which may be of generally conventional construction. Stock 26 is provided with a dead center 28 which is retractable by the knurled hand nut 30 to permit the removal and insertion of arbor 22, and may be locked in place by a conventional locking device 32. The head stock 24 is provided with a tapered bearing sleeve 34, which rotatably receives a shaft 36, the end of which is recessed to receive the driving chuck 38. Shaft 36 is axially fixed in head stock 24 by the collars 40 and 42 respectively and on its outer end also carries an additional pair of collars 46, between which a driving gear 48 and a driving hub 49- are disposed'. Hub 49 is keyed by .key 5| to shaft' 36, and gear 48 is freely rotatable thereon. The outer, face of gear 48 is provided with a plurality of radially extending ribs 52 which cooperate with a springpressed detent 54 to provide a driving relation between gear 48 and hub 49, in any one of a plurality of rotative positions therebetween, corresponding in number and position to the ribs 52. As described in more detail hereinafter, the just mentioned arrangement is provided to eect a rough adjustment of the relative rotative positions of the worm 20 and of the checking mechanism. Detent 54 and the compression spring 56 associated therewith to urge it into engagement with one of the ribs 52, are disposed within a housing 58 secured upon the hub 49. A retracting handle 60 is provided to retract the detent 54 against the force of spring,

56, and permit free relative rotation between hub 49 and gear 48.

Gear 48 is in continuous meshing relation to a larger gear 62, which is carriedupon a shaft 64 which is suitably journaled in a tapered bearing 61 in the machine frame65, and which in turn meshes with a smaller driving pinion 66, supported upon and for rotation by a shaft 68. The

shaft 68 extendstransversely of the machineframe 65, being journaledin bearing bosses 10 formed thereon and at its right hand end, as viewed in Fig. 1, is provided with a manually operable crank 12, which represents a suitable source of driving. power for the machine.

The shaft 64 upon which the gear 62 is mounted extends inwardly of the machine, and at its inner end is provided with a suitable worm 18,

which is secured in place axially thereof between collars 19 and 8|. Worm 18 is in driving relation to a gear 80, the vshaft 82 of which is journaled at its upper end in a boss 84 which is formed in the frame 65, and at its lower end is journaled in a corresponding boss 88 forming part of or secured to the machine frame. Shaft 64 thus acts to drive the checking instrument, in response to rotation of crank 12. The outer end of shaft 64 is provided with a knurled head 86, by which, upon release of detent 54, it may be rotated'to eiect desired adjustments of the relative rotative positions of worm 20 and the checking mechanism.

Instrument table 90 is either formed integrally with or suitably secured upon the upper end of shaft 82, above the level of the machine frame. A machined boss 83 formed von the underside of table 90 rests upon thrust washersl 85, which in turn bears upon a boss 81 extending slightly above the machine frame, thus supporting table 90 in accurately elevated position relative to the axis of the worm 20, and with the axis of shaft 82 directly opposite the axial center of worm 20.

The table 90 is illustrated as generally rectangular in shape, formed in two parts, secured together by studs 9|, and having at its right hand end, as viewed in Fig. 3, an'upstanding projection 92. The instrument and finger-carrying slide 94 is suitably guided for movement longitudinally of table 90 between ways 96 which are secured to'table 90 at opposite sides thereof by studsY 98. A suitable lead screw |00 extends through the projection 92 and is conventionally threaded into slide 94, so that rotation of the former, as by the handle |02, causes slide 94 to move along table 90. Preferably, and as illustrated, a scale |04 is provided, which moves with handle |00, and projection 92 may be provided with a cooperating washer, to afford an accurate indication of the movement of slide 94.

Adjacent the left-hand end of slide 94, as viewed in Fig. 3, a boss |20 extends upwardly and forms a vsupport for a needle bearing |2|, between which and a similar lower needle bearing |23, a finger carrying trunnion |22 is pivoted. The finger |24, which is'suitably secured to trunnion |22, is of bell crank shape, one arm thereof being provided with an adjustably secured stop |28 for cooperation with the operatward and outward movements of the operating element |30, which element is spring biased to an outward position relative to the'extensometer structure. In vaccordance with conventional practice, extensometer |32 may be provided with I a reading scale |40 which is rotatable with respect to the body of the extensometer and which,

therefore, may be set to provide a zero extensoml 9,057,970 eter reading corresponding to any selectedl inward or outward position of the operating element |30. As will be further understood, the zero reading selected for operating purposes is usually one in which the biasing spring associated with the operating member |30 is under compression so that if the element engaged by the operating member |30 is retracted, member |30 follows it,'providing an extensometer reading on one side of the zero point and if the element engaged by the operating member is moved tp force the operating member inwardly of the extensometer, a reading is provided on the opposite signed, are characterized. in that'extensions of.

the tooth faces, drawn in the plane of the axis on the worm, are tangential to a circle concentric with the axis of a worm wheel of mating capacity with theworm, and which may be called the base circle. Accordingly, inv the axis of trunnion |22, about which finger |24 pivots, lies 0n the base circle oi worm 20, and an imaginary line drawn from the point of contact between the face |36 of nger'|24.and a tooth face of an accurately formed worm 20 to the axis of rotation of finger |24, corresponds 4to such a toothface extension. In constructing the machine, the' spacing between the axis of shaft 92, about which table 90 and the structure supported thereby bodily rotates, and the axis of pin |22, about which linger |24 rotates, is made to conform very accurately to the radius of such so-called base circle of the worm. Stated in another way, finger |24-is supported for bodily rotation about the axis ofshaft 02, which coincides with the center of an imaginary worm wheelA adapted for and `positioned in mating relation to worm 20, and thus corresponds to one tooth of such imaginary worm wheel.

Considering now the operation as a whole of the above described elements, it will be under- 'stood that when the machine is not in use, the

table and slide l94\may occupy the central full line position shown in Fig. l, in which the checking finger |24 is withdrawn out of cooperative. relation to the worm 20. As previously stated, the-worm .20 is so adjusted upon arbor 22 between head and tail stocks 24 and 26, that the axial center thereof is directly opposite the centerv of rotation of'` slide 94, that is, directly opposite. the axis of shaft 32. In adjusting worm 20 uponl arbor 22,J it is not necessary to place it inany particular rotative position relative tothe driving mechanism, 'or to the checking finger' |24. After locating worm 20, handle |02 maybe suitably rotated to advance checking finger |24 to the left, as viewed in Fig. 3, bringing it to a point where the face |36 thereof falls between a crown and root of worm 20.. With the parts in the full line relation shown in Fig. 1..such advance of finger |24 brings it to the rightof the end of worm 20, and as a preliminary to such advance,

therefore, detent 34-may be retracted, discon-i necting hub 49 and gear 40, and permitting independent rotation of gear 39 and consequently.

nnger |24, by either the knurled nut 3l, or the operating crank 'I'his rotation may be cony tinued sufficiently to bring finger |24 between Continued two successive turns of worm 20. independent rotation of gear 30 and finger |24, after advancing finger |24 as stated above to a position-where the face |36 thereof lies between a crown and root of worm 20, ultimately brings face |36 into engagement with a .tooth face of worm 20. Preferably, the independent rotation is continued far enough to cause some pivoting of finger |24l about the axis of trunnion |22, which pivoting movement is transmitted to the operating member |30 of extensometer |32 and forces member |30 inwardly of the latter, compressing the spring mechanism thereof and resulting in a dial movement thereof,

If detent 54 is now-released into a position oppositeone of the ribs 52 associated with gear 43, and it being assumed that detent 54 is .directly bearing against one of such ribs, it will be understood that continued movementv of crank 12, or the knurled head 36, results in simultaneous rotation of worm 20 and of the nger carrying slide 94, it being further understood of course that the gearing is such that rotation of slide 94 inv a counter clockwise direction, as viewed in Fig. l, is accompanied by rotation of worm 20 in a direction to cause vcounter clockwise rotation of a worm wheel located. similarly to slide 94.V v'.li'lie initialsimultaneous movement of worm 20. and slide 94 absorbs any backlash which may exist between the members `and the driving elements thereof, so Vthat continued such simultaneous movement occurs in accurate, synchronous rela rotation of worm 20 equal tothe rate at which a worm wheel of mating capacity with wormV 20 would rotate, so that, if the lead of worm'v20 is accurate,V the continued simultaneous advance of worm 20 and slide 94 will not result in any 'rotation-of nger |24 about the axis of itssupportingv trunnion |22. If an inaccuracy or irregularity in the lead of worm 20 occurs at any point along its length,'however, the worm tooth face at the point of such irregularity will tend to either advance ahead of, or fall behind, slide 34, and will either force a pivotal movement of finger |24 about its pivotal axis or will permit an op.-

posite 'rotation thereof about, its pivotal axis underv the influence of the spring mechanism associated with the extensometer. The irregularity, therefore, will appear as a' fluctuation in the position of the pointer |38 of extensometer |32, which instrument will indicate both the de' gree-and direction of the irregularity. vIttwill be noted that the machine may be operated in either direction, in checking a D81'- ticular tooth face. During rotation in one direction,` the worm 20 tends to force the iinger |24 along, and.- during rotation in the other direction,` the tooth face of v worm 20 by receding,

tends topermit the ringer |24 tofollow the tooth face under the influence of the spring mechanism associated with the extensometer.

' The illustrated finger construction is arranged to check a single tooth face at a time, it being understood that the illustrated finger |24 checks the left hand tooth face of theworm 20. It-wiil be understood, however, that forchecking the .lo I

right hand face of worm 20, a similarly constructed finger may be utilized, having an oppositely directed face, the` checking finger being readily insertable and removable, upon removal of set screw |23 associated with trunnion |22.

As previously stated, the tooth face |36 of the checking finger |24 is relieved rearwardly, so that a point of contact is provided between finger |24 and worm 20. Accordingly, the present construction may be used to aiiord an accurate check of the pressure angle of worm 20. In doing this,

the machine may be brought to rest with finger' |24 in engagement with a tooth face of worm 20 at any desired point on the helical path thereof, a zero reading determined, and slide 94 may then be moved longitudinally of the table 90 by member |02, which movement serves to advance lingerV |24 back and forth across the tooth face between the crown and the root thereof. If the pressure angle of the tooth face at the point being checked is accurate, it will be understood that the just mentioned movements will not result in any pivotal movement of finger |24 about the axis of trunnion |22l and will consequently have no effect on the position of the extensometer pointer. Any irregularity in the pressure angle will result in a pivotal movement of finger |24, which pivotal movement will be communicated to and indicated upon extensometer |30 both as degree and as to direction.

The embodiment shown in Figs. 4 through 8 operates on practically the same principles as those upon which the above described embodiment operates, but is distinguished from such rst embodiment in that it is of a so-called universal type, being selectively adjustable to operate upon worms of any desired lead or pressure angle.

Considering Figs. 4 through 8 in detail, the lworm |50 to be checked is supported on an arbor |52 between stocks |54 and |56. The dead center |58, which rotatably supports one end of arbor |52, fits within a tapered chuck I which in turn is slidable within an adjusting sleeve |53. Sleeve |53 is adjustable within a bushing |55 tted into stock |56. An adjusting rod |51 passes through sleeve |53, one end of which is threaded into chuck 5|, and the other end of which carries an adjusting nut |59. Rotation of nut |59 either positively moves center |58 to the right, as viewed in Fig. 7, or permits it to be moved to the left under the inuence of compression spring |60, which is seated between the end of chuck |5| and a shoulder formed in sleeve |53. Sleeve 53 may be locked in any desired position of adjustment axially of bushing |55 by locking stud |6|, the cap nut |62 of which may be turned down to force a pair of locking blocks |64 into jamming relation to chuck |5|. The live center |65 is supported within a bore formed in shaft |66, which is axially fixed, by locknuts |69, within an adjusting sleeve |61. One face of sleeve |61, which is non-rotatively secured in stock |54, is provided with rack teeth |68, which cooperate with a rack pinion |69 secured upon a shaft 4|10 journaled in stock |54. Rotation of pinion |69, as by handle |1|, effects a corresponding axial adjustment of shaft |66 and center |65 within stock |54. Cap nut |12 is provided to lock the assembly in a desired position of adjustment. l

In practice, an adjustment of centers |58 and |65 may be made by backing on lock nuts |62 and |12, effecting an approximate adjustment of center |58 by moving sleeve |53 and/or turning nut |59 suiiiciently to bring center |58 slightly to the left of a desired final position and by rotating handle |1| bringing center |65 to a final position in which the axial center of worm |50'is directly Opposite the center of rotation of the checking mechanism, .later described. 'I'he final movements of center |65 may force center |58 to the right somewhat, as viewed in Fig. 7, this movement being absorbed by spring |60.. Upon completing the adjustments, which may thus be readily made after only a single rough setting of center |58, the lock nuts |62 and |12 may again be turned down to locking positions. In inserting and removing worms, center- |65 may be left locked, and center momentarily retracted by nut |59 against the force of spring |60. y

The shaft |66 carries, on its outer end, an indexing plate |80, held in place thereon by a lock nut |82, and the right-hand face of which, as viewed in Fig. 7, abuts a bracket |84, the hub v| 66 of which is tted over the previously described non-rotative sleeve |61. The periphery of indexing Wheel |80 is provided with a plurality of regularly angularly spaced teeth |88 for cooperation with a detent |90, slidably mounted in a boss |92, formed in the bracket |84.l Detent |80 is provided with a hand grip |94, by which it may be conveniently moved radially outwardly out of engagement with the teeth 88, to permit -rotation of index Wheel |80 and consequently shaft |66 and worm |50. The number of the teeth |88 passed over during such rotation serves as an accurate measure of the extent of the rotation thus imparted to the worm |50.

The head and tail stocks |54 and |56, respectively, are illustrated as formed integrally with a slide 200,-which rides in suitable ways formed in a bed plate 202, and movement thereof along whichmay be effected by a conventional lead screw 204, provided with a manually operable hand wheel 206.

The mechanism for carrying the checking finger 208 comprises a table 2|0, secured aty the upper end of a vertically disposed shaft 2|2, the lower end of which is provided with an indexing wheel 2|4 whichcorresponds in all respects to the previously mentioned indexing wheel |80, except that a substantially greater number of ratchet teeth 2 I6 are provided upon the periphery thereof.

Shaft 2|2 is rotatably supported in a boss 2|8, which may form part of the machine frame, between ball bearing units 220 and 222. `The outer rings of ball bearing units 220 and 222 are secured in desired axial relation relative to the boss 2|8,

.between an up r collar 224 and lower collar 226, both of which are suitably secured to boss 2 8, and a spacing sleeve 228 secured in place relative to boss 2 i8 by studs 230. The inner ball bearing rings are maintained in proper'axial relation to shaft 2|2 by shoulder 234 on shaft 2|2, collar 236 and an inner sleeve 238. The assembly comprising table 2|0 and indexing wheel 2|4 is thus maintained accurately at a desired elevation relative to the axis of rotation of worm |50.

The checking nger 268 is pivotally mounted by a pin 242 upon a slide 244, which rides in suitable ways upon a bed plate 246, and is adjustable longitudinally thereof by a conventional lead screw 248 having a hand wheel 250. Bed plate 246 is adjustably supported upon table 2|0 by studs 252 and 254, which pass through elongate slots 256 and 258-formed in a bar 260, and through lugs 253 and 255 which ride in lateral slots formed in .table plate 246. The nuts (not shown) associated with studs 252 and 254 are disposed in a circular T slot 262, formed in the upper surface of table 2|0, and concentric with the axis of rotation 75 table 2I0.

Prefer bly, and as illustrated, a ,stud l26| is secured t vtable 2|0 at the center thereof and whichis of known and accurate radius. With this arrangement, convenient settings of the bed plate 246 are obtainable by inserting a bar or object also of known width between the pin 26| and the. l

bar 260.

As described with reference to the rst embodiment, the center of rotation of table 2|0 coincides with the center of the base circle of the worm to be checked, and consequently, the just described radial adjustment of bed plate 246 with reference to table 2|0 serves to vary the radius of the base circle.

, As in the first described embodiment, the slide 244 carries an extensometer 264, which may correspond in all respects to the'previously described extensometer |32, and which may be correspondingly associated with the checking lingers 208. A somewhat dierent arrangement is shown, in which the operating member 266 of extensometer 264 bears against a push rod 268, slidably mountedv within a boss 210 secured upon slide 244. The outer end of rod 268 bears against one end of 'a short link 212, pivotally mounted by a pin 214 upon an extension 216 of slide 244. An adjustable stop 218 associated with ingerV 208 bears against the link 212 at a point intermediate its length.

vWith this arrangement, it Will be understocdthat plate 2I4, is mounted in a sleeve 292, which, -in

turn, is suitably secured in a boss 294 formed integrally with anadjusting plate 295. "(Flg. 4.) A compression spring 2 96 seated between an enlarged portion 298 secured upon the shank 300 of detent 290 and the other end of which is seated against av plug 302, which encloses the end of sleeve 292, urges detent 290 tothe left as viewed in Fig. 8, to a position in which it is effective to enter between adjacent teeth of indexingv wheel 2|4 and lock the latter against rotation. A head and is provided .to retract detent 29u against the.

wheel 2|4, whichis also replaceable. It is found l also that the articulated construction provides freer and more positive detent movements.

In order to eifect an adjustment of the rotative position of nnger 208 relative to worm |50 of lesser angular value than 'the angular spacing between adjacent te'eth'on the periphery of indexing wheel 2 I4, provisionis made for bodily rotating detent 290 relative to indexing wheel 2|4.` For this purpose, the supporting plate 296, for detent 290. is

freely rotatable about the previously mentionedcollar 228, which affords a vertical support for plate 295, and is thus rotatableabout the axis of 'decreasing th'e distance between the axis of worm wheel 2|4. The right hand end of plate 295, as viewed in Fig. '1, enters a transverse slot 3|0 formed in a boss 3|2, which may be suitably secured to or formed integrally with the machine frame; and which is also provided with a longitudinally extending slot 3|4, within which the eccentric 3|6 is movable. Eccentric 3|6 is carried upon the shank of an adjusting stud 3|8. A lockingl stud 320 is provided to lock plate 295 in a desired position Awith reference to boss 3|2, by clampingthe upper and lower jaw portions of the latter together. It will be understood that by releasing locking stud 320, and rotating stud '3|8, the movement of eccentric 3|6 effects corresponding rotative movement of plate 295- about the axis of shaft 2|2 as a center.

The operation of the just described embodiment as a whole is substantially as described with reference-to the embodiment shown in Figs. 1, 2, and 3, with the exception thatin the operation of the just described embodiment, the rotation of worm |50 and of the slide 244 is effected, in individual step by' step fashion, by retracting the detents 90 and 290 associated therewith, respectively, and manually turning the indexing wheels |80 and 2|4 through corresponding angles. The indexing 'wheels |80 and 2 I4 are provided with appropriate numbers of notches on the periphery thereof, so that corresponding angular advances thereof, depending upon the gear ratio for which the particular worm |50 being checked is designed, may be effected'.

As will be appreciated from the foregoing, an adjustment of the machine of Figures 4 through 8 to accommodate it to worms adapted for diiering centered distances between the axis of the worm and the axis of the cooperating worm wheel, is effected by moving the slide 200 longitudinally of the bed plate 202, correspondingly increasing or |50 and the axis of rotation of the finger carrying slide 244.' As previously described also, an adjustment of the machine to accommodate worms having differing base circle radiiis made by releasing the locking studs 252 and 254, thus permitting an increase or decrease of theradial distance between slide 244 and the center of rotation of the table 2|0. Adjustment of the machine to accommodate worms designed for diiIerent gear ratios is conveniently made either by utilizing indexing wheels having numbers of ratchet teeth on the peripheries thereof, such that for that dilerent gear ratios, indexing movements may be made past differing numbers of such ratchet teeth, or by--providing different sets of indexing wheels, and selectively replacing the indexing wheels depending upon the gear ratio desired. In utilizing different indexing wheels as previously described, it is desirable to also replace the detents associated therewith, in order that each detent may act positively and correspondingly accurately retain the associated indexing wheel against rotation. l

Figures and 10 'illustrate further modified structures for effecting the. indexingof the check-v ing finger. In the arrangement of Figure 9, the

checking finger 330 is secured upon a slide 332 in the manner previously described. Slide 332 is suitably adjustably supported upon a segmentally lshaped table 334, which carries a segmental rack 336, for cooperation with a suitablelead screw 338 which may be rotated by a handwheel 340, suitably supported within a stationarily mounted boss 342. It will be understood that rotation of hand wheel 340 effects a corresponding rotation l75 of the segmental table 334 about shaft 344 as a base circle of the worm 346 being checked. A slide bar 348, slidable within ways 355 formed in the machine frame, engages the periphery of the segmental table 334. and is frictionally moved within ways 350 in response to rotative movement of tab1e`334. Slide 34| also carries a reading scale 352 which cooperates with a stationarily mounted scale 354 to aord an accurate indication of the rotative movement of segmental table 334.

lWith this arrangement, it will be understood that .a predetermined rotative movement of worm 34,6. as iected by the indexing wheel 356 associated therewith, and which may correspond in all respects to the indexing wheel |80 with referenceto Figures 4 to 8, may be accompanied by a corresponding rotative movement of segmental table 334 and checking finger 330, by suitably rotating hand wheel 340, the angular movement o! which may be read upon the scales 352 and 254. As in the earlier described modifications, if the worm 345 is accurately formed, the corresponding rotation of finger 330 and worm 346 will not result in any pivotal movement of iinger 330 with reference to its slide 332. Any inaccuracy in worm 34B, resulting in such a pivotal movement,A

may be read upon the extensometer 358 in the previously described manner.

In the arrangement of Figure 10, the segmental table 334 is provided with detent asn,

outwardly biased by a compression spring 362, and selectively retractable by a handle 364. Detent 360 cooperates with a series of pins 366, arranged in an arc of a circle concentric with the shaft 344' about which table 334' rotates. It will be understood the pin 366 may be accurately formed so that by notching detent 350 past a desired number thereof a correspondingly accurate angular movement is imparted to table 334' and consequently to the checking iinger 330'. In all other respects, as well as in operation, theembodiment shown'in Figure l0 may be as described with reference to Figure 9.

Although specific embodiments of the present invention have been described in detail, it will be evident that various changes in the form, number and arrangement of parts may be made within the spirit' and scope of the present invention. It Vwill also be evident that variousfeatures of the present invention as hereinbefore disclosed, may be used independently of the complete combination described and that the combination may be utilized for purposes other than the specic purposes described. Accordingly, the foregoing is to be considered in an illustrative and not in a limiting sense.

What is claimed is:

1. Checking mechanism for worms comprising in combination, means for rotatably supporting a worm to be checked; a checking element; and means for mounting said checking elementior bodily rotation about an axis coincident with the axis of an imaginary worm wheel of mating capacity with and positioned in mating relation to said worm.

2. Checking mechanism for worms comprising in combination, means for rotatably supporting a worm .to be checked; a checking element; means for mounting said checking element for bodily rotation about an axis coincident with the axis of an imaginary worm wheel of mating capacity with and positioned in mating relation to said worm; and means for effecting simultaneous and timed rotation of said worm and said checking element.

3. Checking mechanism for worms comprising in combination, means for rotatably supporting a worm to be checked; a checking nger; a table; means pivotally mounting said nger upon said table; and means mounting said table for rotation about an axis coincident with the axis of an imaginary worm wheel of mating capacity with and positioned in mating relation to said worm.

4. Checking mechanism for worms comprising in combination, means for rotatably supporting a worm to be checked; a checking finger; a table; means pivotally mounting said iinger upon said table; means rotatably mounting said table for rotation about an axis coincident with the axis of an imaginary worm wheel of mating capacity with and positioned in mating relation to said worm; and means for effecting simultaneous timed rotation of said worm and said table.

5. Checking mechanism for worms comprising in combination, means for rotatably mounting a worm to be checked; a checking nnger; and means for pivotally mounting lsaid checking iinger for movement into and out of coincidence with a tangent to the base circle of said worm.

Y 6. Checking mechanism for worms comprising in combination, means for rotatably mounting a wormto be checked; a checking finger; means for pivotally mounting said checking iinger for movement into and out of coincidence with a tangent to the base circle of said worm; and means for bodily rotating said checking iinger about an axis coincident with the axis of said base circle.

'1. Checking mechanism for worms comprising in combination, means for rotatably mounting a worm to be checked; a checking finger; means for pivotally mounting said checking linger for movement into and out ofcoincidence with a tangent to the base circle of said worm; means mounting said supporting means for rotation about an axis coincident with the laxis of said base circle; en d means for effecting timed rotation of said Worm and said supporting means.

8. Checking mechanism for worms comprising in combination, means for rotatably mounting a worm to be checked; a checking linger; supporting'means for pivotally mounting said checking iinger for movement into and out of coincidence with a tangent to the base circle of said worm; means mounting said supporting means for rotation about an axis coincident with the axis of said base circle; and means for effecting proportional angular rotative movements of said worm and said supporting means.

9. Checking mechanism for worms comprising means for rotatably supporting a worm to be checked; a checking finger; means mounting said checking nger for bodily rotation about an axis. coincidentA with the axis of an imaginary worm wheel of mating capacity with and positioned in mating relation to said worm; and means for adjusting the spacing between said axis and the axis of said worm.

10. Checking mechanism for worms comprising in combination means for rotatably supportinga'. worm to be checked; a checking ilnger; meansl mounting said checking iinger in coincidence with a tangentto the base circle of said worm; andmeans for adjusting said mounting to accommodate said mechanism to worms of diiering base circle radii.

11. Checking. mechanism -ior worms comprising said checking finger upon said table for movement into and out of coincidence with a tangent to the base circle of said worm; means for effecting proportional rotative advances of said worm and of said table; and indicating mechanism responsive to pivotal movements of said checking t finger;

12. Checking mechanism for worms comprising in combination, means for rotatably supporting a worm to be checked; a checking finger;

means mounting said checking finger in coincifor bodily rotation about an axis coincident with the axis of a worm wheel of. mating capacity with and positioned in'mating relation to said worm;

and means for advancing and retracting said finger along said tooth face Vbetween the crown v and the root thereof.

4supporting said checking finger for bodily rota- A tion about an axis coincident with the axis 012 a worm wheel of `mating capacity with and positioned in mating relation to said worm; a drive shaft; connections between said worm supporting means and said shaft; additional connections between said table and said shaft; means for releasing one of said connections to eect adjust-` ments of the relative rotative positions of said worm and said table;v and means for driving said 15. Checking mechanism for worms comprising in combination means for rotatably supporting said Worm; a checking ringer; a table for supporting said checkingv nger for bodily rotation about an axis coincident with the axis oi? a worm wheel of mating capacity with and positioned in mating relation to said worm; a shaft associated with said wo supporting means; la shaft associated with sad table: an indexing wheel individual to each shaft; and detent mechanism individual to each indexing wheel for locking the associated indexing wheel in selecte rotative positions.

16. Checking mechanism for worms comprising in comblnationmeans for rotatably supportv ing said worm; a checking finger; a table for supporting said4 checkinglinger for bodily rotation about an axis coincident with. the axis of a worm wheel of mating capacity withv and positioned` in mating relation to said worm; a shaft associatedwith said worm supporting means; a

shaft associated with said table; an indexing lwheel individual to each shaft; detent mechanism individual to each indexing wheel for locking the associated indexing wheel in selected rotative positions; and means for bodily moving l one oi' said detent mechanisms relative to its associated wheel to eiect an adjustment of the 17. Checking mechanism-for worms compris- Ving in combination means for rotatably supporting said worm; a checking finger; means includin'g a table for supportingv said checking ilnger for rotation about an axis coincident with the axis of a worm wheel of mating capacity with and positioned in mating relation to said worm; means for eecting proportionate angular advances of said worm and said checking nger, said advancing means including a lead screw, and indicating" means for indicating said angular advance.

18. Checking mechanism for worms comprising in combination means for rotatably supporting said'worm; a checking finger; means including a table for supporting lsaid checking linger for rotation about an axis coincident with the axis of a worm wheel of mating capacity with and positioned in mating relation to said worm; mean for eii'ecting proportionate angular advanceof said worm and said table, said advancing means including a plurality of pins disposed in spacedrelation on an arc of a circle coincident with the axis of rotation of one of said members, and detent mechanism for engagement in the g spaces between said pins.

worm wheel'of mating capacity with andpositioned in mating relation to said worm.

20. Checking mechanism for worms comprising in combination, means for supporting a worm to be checked; a checking element; means for supporting said checking element; mechanism for causing relative bodily movementbetween said worm and checking element about an axis coincident with the axis of an imaginary 4worm wheel of mating capacity with and-positioned in mating relation to said worm; and additionalmechanism for electing simultaneous and time axial rotation oi.' said worm relative to said checking element.

21. Checking mechanism for worms comprising" in combination, means for rotatably mounting a worm to be checked; a checking linger; means for plvotally mounting said checking linger for movement into and out of coincidence with a tangent to the base circle of said worm;

and means for eiecting bodily rotation of said worm and checking linger relative to each other about an axis coincident with the axis of said base circle.

-HARRY PELPHREY.-4 

